Azimuth computer



OCL 8, 1946i J. HILSENRATH ETAL AZIMUTH COMPUTER Filed March 20, 1945APPROXIMATE E'QUATION 0F TIME i-IZ'] 4' Q-Y I INSTRUCTIONS Fasben thepmtractar on Frog! or beck as lettude dictates, then: Set the arrow onthe protrachor to the proper dec|naton. 2. Rotate the protrectorarmuntil it passes through tho inbursecton of the proper latitudeellipse and the hour angle desiredA the Azimuth on bhe pro- 3lSheets-Sheet 1 DEVIATIONS .SAMUEL 62 055 @QM/YL Oct. 8, 1946. J.HILSENRATH ETAL 2,408,776

, ix/ZIAMUTH. COMPUTER "'iled March 2o, 1945 3 sheets-sheet 2 la /z z 21JULY FIN S04/TH LAr/TUDE Z E 1Ml NORTH LATI use me INNER ,vor oFFiel/nes Fon Hol/R ANGLE .uva 7 ANTANES Y NIGEL HETELGEI Ik ALDEEARANJose-,5w H/LsE/veAr/f l SAA/'10a 620,55

0d- 3# 1946-.` J. HlLsl-:NRAT'H Er'AL 4085776 v AZIMU'ITH COMUTER yF'ilqd uarch zo, 1945 :s sheets-snee; :s

TIME BODY DEViATIONS l l nus valo' ula' i IIJ/1l l 4 13:51/ nia! Y zamanunon dose/H `H1LsfNRATH Muna Glas:

Patented Oct. 1946 f STAT 2,408,770 ics v .f AZIMUTHcomic-TE,Itv l IY@resesi1L,r,1i1,sematl1 and, saisissante,

` v'I Lnted States Navy" Applicaticnlltarch 20, 194.5,1Seria1N9`.';5;3.82$

' i3 claims. (glissa-1i) (Granted "This invention relatesgenerally `tonavigation instruments, and particularly `to "devices for nsolvingspheri'cal'triangles,

.'In the art of naviga ion it is a .constantly re- .,cnrring problem tosolve spherical triangles for one .angle when ,others .are known.Compass adjusters must frequently determine azimuth of .some celestialbody vfor purpose of :checkingthe indication of thecompassunderobservation.

It is common practice in such cases to start with such factors ashourangle', latitude of thev observer and declination oftheobserved body,-anddetermine itsazimuthloy reference to various tables, charts, etc. ,Acompassadluster will voften havefa' number of azimuth :cards or curvesca lcnlatedjfor certain locations.

Inthese various determinations of azimuth, in-

vamended April 30, 1928;

'terpolations are oftennecessary, and the cal-cu- 'lationsare such )thatan errorearly 1in the process ymaybe multiplied as ,thel calculationproceeds, leading 'toerrors of intolerable magnitude. Y`

Atjbest the calculations are tedious and time Y consuming.; 'hereis aneed .lor some means for .determining azmuths rapidlyandV with a minimlm@h anpe-or errors 4such as vare commoninV 'ihenrdiarymethods used...

Itis; therefore, object of ltheinventi'on to undervthe act of March '-3,11883,- as

The. difference in the grids 91,1 .from an@ .back of the *base'is onlyvin the scope of jlatitudes overed. On the baclg `are in agilredellipses Afor latitudes of from 40, to 6Qf ,^v{hilelatitudes of 0 to 45are marked on front side. Front and back grids will be registered so@thatthe protractor may be used oneither side.

Mounted 'for sliding lparallel to .the airis '5 xris a *protractor J of,transparent material. A. .boit ,s 'with nut :9 lits thrnigh thepmtractor and may Slide .a slot Al0 ,Glut throilgh hase ,I parallel t0the axsnd togthelbottcmedgeof the hase. In the form ,Shown `the loweredge ,of ,the V prQtractor lovvenedge'of .thelcasetto assist in holdingthe .protractor I.in prpperrelatiori to thebase. y'Itssca'le isindicated at lz. Prorsctor erm L3 with ,itsirlsexllne Missiv- OtedatlIto @thnrotractcr inpsuch iashlon 'that the pivot 'l'5`flies,dretlysovrer yaxis J5. when Vthe vligtractor is .mounted ofn .the-basaA .line rlllv is "marked the motractor rroieting vertically provideajsimple and ,practical vdevice capable of facile anldrapiddeterminations of azimuth, when local` apparentY time or, hour angle',vlatitude'and de clnationareknown. ,r 1 '1t isanfobjectto provide adevice sufcient in itself 'for accurate solution of spherical triangles,avoiding gany need for reference tobully volumes crazimuth tables, etc.

rAfurther lobject ofourinventicn is ,to provide an razimuth ,computerWhich vwillgive true f az'- `mutihs. y Y Q'Acldtional` obj ects willappear when the description''sconsideredl lnthedrawings: e Y

Figure 1 is arepresen'taton of apreferiredjforrn 'of ourazimuthcomputer, showing the protractor .mounted on vthe reverse side.ofthe'hase.

FigureZ is a section alongjline.Z-fZQfFigure 1. FigureB indicatesV theobverse side of tliebase .onlyofthe computer.

As indicatediin r`Figure '1, our `azimuth computer includesanop'aque'base vI on vvhichis printed .or

otherwise.suitablymarked a grid`2. -I'hegridis and latitude composedofhour anglejliyperholasr 3 ellipses "4 "in .suitablejincrements Theiine5, which we Jterm the axis'of 'the grid, isv an axis ofthe'confocalhyprbolas; and ellipses,4and'isjpa'rallelto'the'lower'edgeof the basel.' 'Hyperbolas' are `nbered'inside and outside *the grid. v"Latitude ellipses 4arenumberedalong the `axis y5. vSinc'e the latitude Aellipses also-serve "toi'measu-re declination; the-indications? along axis 6 :areAAbroughtdov/n and@repeatedf at sca-le 6 )for convenience inioperation.Y

5 ,21nd thatdeclinaticn may beraad by, considera; tion o f line Ilrelative toscale 6,. ,Bositongf indexu lrie I4 -will beraad; on suitable,scales .con

the cuter edgesv of thenrotractor. V,In ,orderithat the device j mayceused. for jNortn and'onthlati- ,tudes and Lfor vanyjhourangle or localapparent tme,"thevariou s fscales vvill be suitablyllumbe'lled 'andifulldirectionsniarked explaining operation.

jequationf i A @coordinates-,alter N'ot all `rthe'-rrlarkings employedare shown toavoid conf-using detai1.

The theoryofithedevices as follows: In the grid 2, latitude ellipseslaredefinedby lthe equation si' wz S'il lil-tanti" l Hour angle hyperbolas hare dened JAbythe altitude ellipses and ihonr angle systems of lrhvperbolas are l`marked `01:1 rw and is @ordinate axes '.-Theiinterseetionnf .a,1abli.tude ellipse f th an hourranglehyperbole-siennes .a point `zrvgllcse nasce-lysine y: @tanil'fcosh`where :d=. :dec1ination,. a' line drawn, such zrepresents the 4azimuthfof ia '-ibody -of r` declination d from 'latitudeT laathour langleyence to any books or charts.

, axis.

Il crosses scale 6 at the proper declination. Arm

I3 will then be moved to locate line I4 at the intersection of theellipse and hyperbola representing the known latitude and hour angle.Line :I4 will then indicate on the scale of the protractor the azimuth,commonly referred to as Zn. Y

In Figure 1, the instrument is set to determine azimuth when:

Latitude=56 S. Declination=15 S. Hour angle=2h36m E.

lAzimuth reads on protractor I as 0510.8.

As is apparent, the entire problem is solved by the one instrument.There is no need for refer- To facilitate this operation, directions andrules may be printed on the device. Some are shown, others omitted forclarity of illustration. The computer may be used for any latitude ordeclination to 60 either north or south; Azimuth is found directly asObviously many changes are permissible while adhering to the principlesof the invention as expressed in the following claims.

' The invention described herein may be manufactured and used by` or forthe Government of the United States of America for governmental purposeswithout the payment `of any royalties vthereon or therefor. L We claim:

j y 1. In an azimuth computer, a base member comprising a grid composedof confocal hour angle hyperbolas and latitude ellipses, said base:member having a plurality of bearing surfaces parallel to the minoraxis ofthe ellipses, a protractor member mounted onthe base member, saidprotractor member having means cooperat- 'ing with and engaging said.bearing surfaces, whereby said protractor member is slidably butnon-rotatably moveable parallel'to said minor 2. In an azimuth computer,a base ,member comprising a grid composed of confocal hour anglehyperbolas and latitude ellipses, said base member having a plurality ofbearing surfaces parallel to the minor axis of the ellipses, aprotractor member mounted on the base member, said protractor memberhaving means cooperatl point coinciding with' said minori axis wherebythe pivot may move along said minor axis, said f bearing surfaces andsaid cooperating and engaging means including an edge on one of saidmembers parallel to said minor axis and a lip on The protractor willthen be secured 4. In van azimuth computer, a base member comprising agrid composed of confocal hour angle hyperbolas and latitude ellipses,said base member having a plurality of bearing surfaces parallel to theminor axis of the ellipses, a proing with and engaging said bearingsurfaces,

whereby said protractor member is slidably but non-rotatably moveableparallel to said minor axis, and an arm pivoted on the protractor, at apoint coinciding with said minor axis whereby the pivot may move alongsaid minor axis.

3. In an azimuth computer, a base member comprising a gridcomposed ofconfocal hour angle hyperbolas and latitude ellipses, said base memberhaving a plurality of bearing surfaces parallel to the minor axis of theellipses, a protractor member mounted on the base member, saidprotractor member `having means cooperating with and engaging saidbearing surfaces, whereby said protractor member is slidably butnon-rotatably moveable parallel to said minor axis, and an armpivotedonthe protractor, at a tractor member mounted on the base member,

said protractor member having means cooperating with and engagingsaidbearing surfaces, whereby said protractor member is slidably butnon-rotatably moveable parallel to said minor axis, and an arm pivotedon the protractor, at a point coinciding with said minor axis wherebyAthepivot may move along said minor axis, said bearing surfaces and saidcooperating and engaging means including a slot in at least one of saidmembers and a threaded bearing pin and locking nut in the other of saidmembers.

5. In an azimuth computer, a base member comprising a grid composed ofconfocal hour angle hyperbolas and latitude ellipses, said base memberhaving a plurality of bearing surfaces parallel to the minor axis of theellipses, a protractor member mounted 0n the base member, saidprotractor member having means cooperating with and engaging saidbearing surfaces, whereby said protractor member is slidably butnon-rotatably moveable parallel to said minor axis, and an arm pivotedon the protractor, at a point coinciding with said minor axis wherebythe pivot may move along said minor axis, said bearing surfaces and saidcooperating and engaging means including an edge' on one of said membersparallel to said minor axis and a lip lon the other of said membersbearing against and engaging with said edge, anda slot in at least oneof saidmembers and a threaded bearing pin and locking nut in the otherof said members.

' 6. In an azimuth computer, a base member comprising a grid composed ofconfocal hour angle hyperbolas and latitude ellipses, said base memberhaving a plurality of bearing surfaces parallel to the minor axis of theellipses, a protractor member mounted on the base member,

said protractor member having means cooperating with and engaging saidbearing surfaces, whereby said protractor member is slidably butnon-rotatably moveable parallel to Said minor axis, and an arm pivotedon the protractor, at a point coinciding with said minor axis wherebyvthe pivot may move along said minor axis, said bearing surfaces andsaid cooperating and engaging. means including an edge on one of said`members parallel to said minor axis and a lip on the other of saidmembers bearing against and engaging with said edge, and a slot in atleast one of said members and a threaded bearing pin and locking nut inthe other of said members, the declination axis being duplicated belowtheQminor axis, an indicator means on said protractor member readingonsaid duplicate declination axis, an indicator means on said protractorlarm comprisinga line extendingV from the pivot, said protractor memberbeing'offset'between said duplicate declination axis and said minoraxis, said protractorarm being pivoted to the bottom of saidVprotractormember between `said protractor member and said base memberwith said indicator means V.closelyVv adj'icent `the base member therebyavoiding kparallax between said indicator means and said grid.

7. In an azimuth computer, a base member comprising a grid composed ofconfocal hour angle hyperbolas and latitude ellipses, said base memberhaving a plurality of bearing surfaces parallel to the minor axis of theellipses, a protractor member mounted on the base member, saidprotractor member having means coop-erating with and engaging saidbearing surfaces,

` whereby said protractor member is slidably but non-rotatably moveableparallel to said minor axis, and an arm pivoted on the protractor, at apoint coinciding with the pivot may move along said minor axis, thedeclination axis being duplicated below the minor axis, an indicatormeans on said protractor member reading on said duplicate declinationaxis, an indicator means on said protractor arm comprising a lineextending from the pivot, said protractor member being offset betweensaid duplicate declination axis and said minor axis, said protractor armbeing pivoted to the bottom of said protractor member between saidprotractor member and said base member with said indicater means closelyadjacent the base member thereby avoiding parallax between saidindicator means and said grid.

8. In an azimuth computer, a base member comprising a grid composed ofconfocal hour angle hyperbolas and latitude ellipses, said base Ymemberhaving a plurality of bearing surfaces parallel to the minor axis of theellipses, a protractor member mounted on the base member, saidprotractor member having means cooperating with and engaging saidbearing surfaces,

whereby said protractor member is slidably but non-rotatably moveableparallel to said minor axis, 'said bearing surfaces and said cooperatingand engaging means including an edge on one of said members parallel tosaid minor axis and a lip on the other of said members bearing againstand engaging with said edge.

9. In an azimuth computer, a base member comprising a grid composed ofconfocal; hour angle hyperbolas and latitude ellipses, said base memberhaving a plurality of bearing surfaces parallel to the minor axistractor member mounted on the base member, said protractor member havingmeans cooperating with and engaging said bearing surfaces, whereby saidprotractor member is slidably but non-rotatably moveable parallel tosaid minor axis, said bearing surfaces and said cooperating and engagingmeans including a slot in at `least one of said members and a threadedbearing pin and locking nut in the other of said members.

10. In an azimuth computer, a base member comprising a grid composed ofconfocal hour angle hyperbolas and latitude ellipses, said base memberhaving a plurality of bearing surfaces parallel to the minor axis of theellipses, a protractor member mounted on the base member, saidprotractor member having means cooperating with and engaging saidbearing surfaces, whereby said protractor member is slidably butnon-rotatably moveable parallel to said minor axis, said bearingsurfaces and said cooperating and engaging means including an edge onone of said members parallel to said minor axis and a lip on the otherof said members bearing against and engaging with said edge, a slot inat least one of said members and a threaded bearing pin and locking nutin the other of said members.

11. In an azimuth computer, a reversible base of the ellipses, a pro-`said minor axis whereby member comprising a grid composed of confocalhour angle hyperbolas and latitude ellipses, the grid on one side ofsaid base member being a `continuation of the other side thereof, saidbase member having a plurality of bearing surfaces parallel tothe minoraxis of the ellipses, a protractor member mounted on the base member,said protractor member having means cooperating with and engaging saidbearing surfaces, whereby said protractor member is slidably butnon-rotatably moveable parallel to said minor axis.

l2. In an azimuth computer, a reversible base member comprising a gridcomposed of confocal hour angle hyperbolas and latitude ellipses, thegrid on one side ofsaid base member being a continuation of andregistered with the grid on the other side thereof, said base memberhaving a plurality of bearing surfaces parallel to the minor axis of theellipses, a protractor member mounted on the base member, saidprotractor member having means cooperating with and engaging saidbearing surfaces, whereby said protractor member is slidably butnon-rotatably moveable parallel to said minor axis, said bearingsurfaces and said cooperating and engaging means including an edge onone of said members parallel to said minor axis and a lip on the otherof said members bearing against and engaging with said edge, and a slotin at least one of said members and a threaded bearing pin and lockingnut in the other of said members enabling said protractor member to beslidably but non-rotatably secured on either side of said base member.

13. In an azimuth computer, a reversible base member comprising a gridcomposed of confocal hour angle hyperbolas and latitude ellipses, thegrid on one side of said base member being a continuation of andregistered with the grid on the other side thereof, said base memberhaving a plurality of bearing surfaces parallel to the minor axis of theellipses, a protractor member mounted on the base member, saidprotractor member having means cooperating with and eny. gaging saidbearing surfaces, whereby said protractor member is slidably butnon-rotatably moveable parallel to said minor axis, and an arm pivotedon the protractor, at a point coinciding with said minor axis wherebythe pivot may move along said minor axis, said bearing surfaces and saidcooperating and engaging means including an edge on one of said membersparallel to said minor axis and lip on the other of said members bearingagainst and engaging with said edge, andv a slot in at least one of saidmembers and a threaded bearing pin and locking nut in the other of saidmembers enabling said protractor member to be slidably but non-rotatablysecured on either side of said base member, the declination axis beingduplicated below the minor axis, an indicator means on said protractormember reading on said duplicate declination axis, an indicator means onsaid protractor arm comprising a line extending from the pivot, saidprotractor member being offset between said duplicate declination axisand said minor axis, said protractor arm being pivoted to the bottom ofsaid protractor member between said protractor member and said basemember with said indicator means closely adjacent the base memberthereby avoiding parallax between said indicator means and said grid.

JOSEPH HILSENRATH. SAMUEL GLOBE.

and registered with the grid on f

